Add altimeter app.

apps/CMakeLists.txt

@@ -3,4 +3,5 @@ add_subdirectory(tcp_server)
 add_subdirectory(adc_dma_chain)
 add_subdirectory(piccolosdr)
 add_subdirectory(barometer)
-add_subdirectory(filesystem)
+add_subdirectory(filesystem)
+add_subdirectory(altimeter)

apps/altimeter/CMakeLists.txt

@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 3.12)
+
+project(pico-altimeter)
+
+add_executable(altimeter test.c)
+
+target_link_libraries(altimeter LINK_PUBLIC littlefs bmp390)
+
+pico_add_extra_outputs(altimeter)
+
+pico_enable_stdio_usb(altimeter 1)
+pico_enable_stdio_uart(altimeter 0)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

apps/altimeter/test.c

@@ -0,0 +1,173 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "pico/stdio.h"
+#include "pico/stdlib.h"
+
+#include <lfs_rp2040.h>
+#include <bmp390.h>
+
+static lfs_t lfs;
+static struct lfs_config cfg;
+
+uint32_t read_boot_count(bool increment) {
+    uint32_t boot_count = 0;
+    lfs_file_t boot_count_file;
+    lfs_file_open(&lfs, &boot_count_file, "boot_count", LFS_O_RDWR | LFS_O_CREAT);
+    lfs_file_read(&lfs, &boot_count_file, &boot_count, sizeof(boot_count));
+
+    if (increment) {
+        boot_count += 1;
+        lfs_file_rewind(&lfs, &boot_count_file);
+        lfs_file_write(&lfs, &boot_count_file, &boot_count, sizeof(boot_count));
+    }
+
+    lfs_file_close(&lfs, &boot_count_file);
+
+    return boot_count;
+}
+
+void reset_recordings() {
+    lfs_format(&lfs, &cfg);
+    lfs_mount(&lfs, &cfg);
+}
+
+void start_altimeter_mode() {
+    uint32_t boot_count = read_boot_count(true);
+    printf("Current recoding index: %d\n", boot_count);
+
+    char filename[64] = {0};
+    sprintf(filename, "REC_%03d", boot_count);
+    printf("Creating recording file: %s\n", filename);
+    lfs_file_t recording_file;
+    lfs_file_open(&lfs, &recording_file, filename, LFS_O_RDWR | LFS_O_CREAT);
+
+    bmp_t bmp;
+    bmp.oss = 5;
+    bmp.i2c.addr = 0x77;
+    bmp.i2c.inst = i2c1;
+    bmp.i2c.rate = 400000;
+    bmp.i2c.scl = 3;
+    bmp.i2c.sda = 2;
+
+    printf("Starting BMP390...\n");
+    if (!bmp_init(&bmp)) {
+        return;
+    }
+
+    while(true) {
+        if (!bmp_get_pressure_temperature(&bmp)) {
+            continue;
+        }
+
+        printf("---------------------------------------------\n");
+        printf("Temperature (ºC): %f\n", bmp.temperature);
+        printf("Pressure (hPa): %f\n", bmp.pressure);
+        printf("Altitude (m): %f\n", bmp.altitude);
+
+        lfs_file_write(&lfs, &recording_file, &bmp.temperature, sizeof(float));
+        lfs_file_write(&lfs, &recording_file, &bmp.pressure, sizeof(float));
+        lfs_file_sync(&lfs, &recording_file);
+
+        sleep_ms(250);
+    }
+
+    lfs_file_close(&lfs, &recording_file);
+}
+
+void dump_recording_file(uint32_t index) {
+    printf("<======");
+
+    char filename[64] = {0};
+    sprintf(filename, "REC_%03d", index);
+
+    lfs_file_t recording_file;
+    lfs_file_open(&lfs, &recording_file, filename, LFS_O_RDWR);
+
+    int32_t file_size = lfs_file_size(&lfs, &recording_file);
+
+    uint8_t read_buffer[128];
+    for (int32_t seek = 0; seek < file_size; seek += sizeof(read_buffer)) {
+        lfs_file_read(&lfs, &recording_file, read_buffer, sizeof(read_buffer));
+        
+        for (int32_t i = 0; i < sizeof(read_buffer); i++) {
+            printf("%02X", read_buffer[i]);
+        }
+    }
+
+    lfs_file_close(&lfs, &recording_file);
+
+    printf("======>\n");
+}
+
+int main(void) {
+    stdio_init_all();
+
+    sleep_ms(2500);
+
+    printf("Hello from Pi Pico!\n");
+
+    printf("Checking hardware capabilities...\n");
+    lfs_rp2040_init(&cfg);
+
+    printf("Mounting filesystem...\n");
+    if (lfs_mount(&lfs, &cfg)) {
+        lfs_format(&lfs, &cfg);
+        lfs_mount(&lfs, &cfg);
+    }
+
+    printf("Filesystem Usage (blocks): %d/%d\n", lfs_fs_size(&lfs), cfg.block_count);
+    printf("Automatically starting altimeter in 5 seconds...\n");
+    printf("Press 'X' to enter in CLI mode.\n");
+
+    int elapsed = 0;
+    int iteration_time = 50;
+    while (getchar_timeout_us(0) != 'X') {
+        sleep_ms(iteration_time);
+        elapsed += iteration_time;
+
+        if (elapsed >= 5000) {
+            start_altimeter_mode();
+        }
+    }
+
+    printf("Available recordings: %d\n", read_boot_count(false));
+    printf("Commands:\n");
+    printf("    D - Dump recording file.\n");
+    printf("    + - Reset recording counter.\n");
+
+    uint32_t index;
+
+    while(true) {
+        char cmd = getchar_timeout_us(0);
+
+        switch(cmd) {
+            case 'D':
+                printf("Type the recording index.\n");
+                scanf("%d", &index);
+
+                if (index >= read_boot_count(false)) {
+                    printf("Index out of range.\n");
+                    break;
+                }
+
+                printf("Dumping recording #%d\n", index);
+                dump_recording_file(index);
+                break;
+
+            case '+':
+                printf("Reseting recordings...\n");
+                reset_recordings();
+                printf("Done! Available recordings: %d\n", read_boot_count(false));
+                break;
+
+            default: 
+                sleep_ms(30);
+                break;
+        }
+    }
+
+    lfs_unmount(&lfs);
+
+    return 0;
+}

apps/altimeter/visualize.py

@@ -0,0 +1,36 @@
+import numpy as np 
+import matplotlib.pyplot as plt
+from matplotlib.ticker import FormatStrFormatter
+
+# Convert HEX file to BIN.
+# cat D4.hex | xxd -r -p > D4.bin
+
+data = np.fromfile('./D5.bin', dtype=np.float32)
+temp_x = data[0::2]
+pres_x = data[1::2]
+alt_x = ((((1013.25 / pres_x) ** (1/5.257)) - 1) * (temp_x + 273.15)) / 0.0065
+y = np.linspace(0, len(temp_x) / 4, len(temp_x)) 
+max_alt_del = np.max(alt_x) - np.min(alt_x)
+
+fig = plt.figure()
+
+ax = fig.add_subplot(111, label="1")
+ax2 = fig.add_subplot(111, label="2", frame_on=False)
+
+ax.set_title(f"Kite Altimeter - 1st Flight | Max Altitude Delta = {max_alt_del:.2f} m")
+ax.plot(y, temp_x, color="fuchsia", linewidth=1)
+ax.set_ylabel('Temperature (ºC)', color="fuchsia")
+ax.yaxis.set_label_position("right")
+ax.yaxis.tick_right()
+ax.tick_params(axis='y', colors="fuchsia")
+ax.yaxis.set_major_formatter(FormatStrFormatter('%.0f'))
+
+ax2.plot(y, alt_x, color="#50fa7b", linewidth=1)
+ax2.set_xlabel("Time (s)")
+ax2.set_ylabel("Altitude (m)", color="#50fa7b")
+ax2.tick_params(axis='y', colors="#50fa7b")
+ax2.yaxis.set_major_formatter(FormatStrFormatter('%.0f'))
+
+plt.savefig('altitude.png', dpi=300)
+
+plt.show()